Ore flotation



Patented July 29, 1941 "DRE FLOTATION John C. Woodhouse, Cragmere, DeL, assignor to E. I. du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware No Drawing. Application May 25,1940,

Serial No. 337,197

, 7 Claims.

This invention relates to the beneficiation of mineral ores by flotation and to reagents for effecting the same. More particularly, it relates to a new class of reagents having both frothing and collecting powers. Still more particularly, it relates to a new class of reagents useful for the beneficiation of both sulfide and nonsulflde ores.

It has heretofore been suggested to employ compounds having balanced lipophile and hydro-.

phile groups as reagents in froth flotation processes. It has now been found that a new class of reagents more fully described hereinafter is surprisingly effective in flotation processes.

It is an object of this invention to provide a new class of reagents for mineral beneficiation. It is a further object of the invention to provide new reagents having both frothing and collecting powers. Other objects will be apparent from a consideration of the ensuing description and ppended claims.

According to this invention, mineral ores may be concentrated in froth flotation processes by with an organic chemical substance, having the following general formula: CHZOHCOOR, whereagitating and aerating an aqueous pulp thereof in R represents an alkyl or an alicyclic radical which may also contain functional groups, the

number of carbon atoms in R being at least one and not more than twelve.

In the above general formula, R may represent a simple alkyl radical, such as methyl, propyl, isobutyl, octyl, and dodecyl. It may also represent an alicyclic radical, such as cyclobutyl, cyclopentyl, cyclohexyl, and cyclooctyl. B. may still further contain functional groups, such as ether-oxygen, hydroxyl, and the like; for example, the esterifiable radicals derived from ethylene glycol, diethylene glycol, triethylene glycol, and the mono-ethers thereof, from methoxymethoxy ethanol, glycerol and others thereof, and from similar compounds.

Compounds included within the scope of this invention are the alkyl esters of glycolic acid, wherein the alkyl radical contains not more than twelve carbon atoms, such as the methyl, ethyl, propyl, isobutyl, cyclohexyl, octyl, and dodecyl glycolates. It has been found that isobutyl glycolate is a preferred and particularly valuable reagent for the purpose. Other compounds, which although not within the above general formula, are believed to possess utility as flotation agents, are the alkoxv acetates, wherein the alkyl substituent of the alkoxy radical is methyl, ethyl,

propyl, isobutyl, cyclohexyl, octyl, dodecyl, or I other group containing from one to twelve carbon are the acyloxy acetic acid esters, wherein the acyl radical is formyl, acetyl, propionyl, isobutyryl, or homologous acyl radical containing not more than twelve carbon atoms.

In general, the reagents of this invention may be utilized according to the usual practice in the art. It has been found to be preferable to employ from 0.05 to 2.0 pounds of reagent per ton of ore treated, although these values are not to be considered limitative. Larger or smaller amounts may be used. However, when larger amountsare used, the benefits to be derived therefrom are not directly proportional. than 0.05 pound per ton are .used, a noticeable improvement is observed, but recoveries tend to be reduced. The following examples serve to illustrate the practice of this invention, but it is not limited to the described specific embodiments.

Example I.--The ore for this example was a micaceous limestone, which is used in the production of Portland cement and whose mineral composition'is described in detail in a publication 1 by Miller and Breerwood (American Institute of pyrite, limonite, apatite, and amorphous carbonare present in small quantities.

The limestone was crushed in a small jaw crusher and then reduced to minus 40-mesh by means of a Braun disc pulverizer. A slurry was prepared by grinding one kilogram of this material for ten minutes in a one-gallon porcelain jar mill with oneliter of water and three kilograms of flint pebbles. For the flotation operation, the ground slurry was then transferred to a standard Denver Laboratory flotation machine of onekilogram capacity and was made up to a pulp volume of 4.5 liters by the addition of water. As the agitation of the pulp commenced, 0.062 gram of isobutyl glycolate, corresponding to 0.124 lb./ton of ore, was added and the agitation con tinued as to condition the pulp for one minute.

To this slurry 0.246 gram of oleic acid, corresponding to 0.492 lb./ton of ore, was added whereupon a well-textured froth, well-loaded with'calcite formed immediately. The froth was scraped into a collecting pan until the frothing had practically ceased, which required about six minutes. The overflow or calcite concentrate and the underflow or tailings were filtered, dried, weighed and analyzed for their. calcium carbonate con- When smaller amounts tent. The results are summarized in the following table.

From the above table, it is apparent that a calcium carbonate concentrate of 94.5% is obtained from a heads or feed to cell assaying 81.1%

CaCOa.

The desirable fro'thing property of the esters of hydroxyacetic acid is strikingly borne out when the same operation is performed with oleic acid alone. The resulting thick, scum-like froth lacks the collecting power and froth texture obtained in the above example.

The superior frothing properties of isobuty glycolate is strikingly indicated when compared to a similar flotation operation .using 0.062 gram or 0.124 lb./ton of a refined pine oil in place of isobutyl glycolate in which case the amount of concentrate floated was only 301 grams or 54% by weight of that floated with isobutyl glycolate.

Example II .-One kilogram of micaceous limestone prepared in a manner similar to that described in Example I was subjected to a similar flotation operation using 0.0965 gram of methyl glycolate, corresponding to 0.193 1b./ton of ore, and 0.246 gram of oleic acid, corresponding to 0.492 lb./ton of ore.

In this run a 95.6% grade of calcium carbonate concentrate was obtained from a heads or cell feed assaying 80.4% CaCOS.

Example [IL-One kilogram of a micaceous limestone prepared in a manner similar to that described in Example I was subjected to the same flotation operation using 0.075 gram (0.15 lb./ton) of cyclohexyl glycolate and 0.24 gram (0.48 lb./ton) of oleic acid. The results of this run were summarized in the following table.

CaCOa Weight,

grams Product Percent Distribution Concentrate Teiiings Heads 09.00: Weight, grams Product Percent Distribution Concentrate Tailings Heads 7 Example V.'Ihe run described in Example I with micaceous limestone was repeated with 0.075 gram (0.15 lb./ton) of dodecyl glycolate dissolved in 0.75 gram of alcohol and 0.24 gram (0.48 1b./ton) oleic acid. A calcite concentrate of 95.61% was obtained from a heads or cell feed assaying 80.30% CaCOZS.

Example VI.--In this run isobutyl glycolate was used with a collector of the type described by Lenher in U. S. 2,132,902 which is especially suitable for floating silica and silicate minerals.

A 1300 gram sample of hematite iron ore washer tailings, containing about 20% moisture and consisting of about 76% ZOO-mesh material, was ground further to about ZOO-mesh in a laboratory iron rod mill and then deslimed prior to flotation. The ground slurry was transferred to a standard Denver Laboratory machine of one-kilogram capacity and subjected to a flotation operation usingisobutyl glycolate and the crude amine hydrochloride derived from coconut fatty acids, known as Lorol amine hydrochloride. Two separate fractions, designated overflow and rniddlings, were removed. The results are summarized in the following table.

Example VI[.-One kilogram of Montana copper sulfide ore was crushed in a small jaw crusher and then reduced to minus 40-mesh by means of a Braun disc pulverizer. A slurry was prepared by grinding further in a porcelain jar mill with 3 kilograms of flint pebbles and 1 liter of water. This was then transferred to the flotation cell in which it was conditioned with 3.5 grams (7.0 lb./ton) of lime for five minutes, 0.070 g, (0.14 lb./ton) of isobutyl glycolate for one minute, and finally with 0.10 g. (0.20 lb./ton) of potassium ethyl xanthate for one minute. The resulting froth was collected into a pan, filtered, dried. weighed and analyzed.

In this run the grade was increased from 7.55% Cu to 30.34% with good recovery.

Example VIII.-One kilogram of a Colorado molybdenum ore was crushed in a small jaw crusher and then-reduced to minus 40-mesh by means of a Braun disc pulverizer. A slurry was prepared by grinding this material in a porcelain jar mill with 3 kilograms of flint pebbles and 1 liter of water. This was then transferred to the Denver flotation cell and subjected to a flotation operation using 0.175 g. of isobutyl glycolate. The resulting molybdenite concentrate, which constituted the overflow, and the underflow or tailings were filtered, dried, weighed, and analyzed for molybdenum content. The results of this run are summarized in the following table.

In this run the grade of the molybdenite was increased from a feed running 0.675% Mo to a concentrate assaying 10.45% Mo, indicating the good collecting property of isobutyl glycolate.

In these examples it is understood that in order to obtain higher grades of concentrates it is only necessary to'retreat the concentrates with. more of the flotation reagents of this invention.

In carrying out the flotation process by the use of the class of compounds with which this in-' vention is concerned, any of the Well known types of flotation cells may be used. The ratio of pulp solids to water may vary from about 1:1 to about 1:6 or more. The amount of the glycolic ester used by itself with such readily floated minerals as molybdenite or used in conjunction with other classes of flotation agents will vary depending upon the amenabilityof the ore to flotation and the grade of the ore treated. 'In general, the amount will be between 0.05 pound and 2.0 pounds per ton of ore, but in some cases somewhat smaller or larger quantities may be required. As indicated by the examples, the glycolic esters can be used with several varieties of collecting agents such as fatty acids and soaps, longchain alkyl sulfates, amines and amine salts, xanthates, etc. They may also be used in mixtures of oils, fatty acids, etc. or in solvents, or in emulsions.

The particular reagents of the class herein described are not limited to beneficiation'of the minerals given in the examples. Both sulfide and nonsulfide minerals may be beneflciated. In addition to the ores used in the examples the compounds may be used in-beneficiation of coal,

graphite, lead, zinc, phosphate and other ores and mineral mixtures.

Depending upon the types of collectors, i. e., fatty acids and soaps, or amine products, they may be used either for direct flotation, i. e. where used in flotation processes employing conditioning'or dispersing agents. Such agents may be sodium silicate, sodium phosphate and other inorganic chemicals commonly used in flotation practice, and the dispersing agents may be lignin sulfonic acid, tannic acid, starch and protective colloids.

While the above examples describe flotation operations using non-saline pulps, it is understood that pulps made from brines or saturated solutions, such as in the flotation of the potash ore sylvinite, are within this invention.

What is claimed as new and desired to be protccted by Letters Patent-is:

1. In a process for concentrating mineral ores by froth flotation, the step of agitating and aerating an aqueous pulp of the said ore with an organic chemical substance having the following general formula: CHzOHCOOR wherein R represents alkyl and alicyclic radicals, the sum of the carbon atoms in R being at least one and not more than twelve.

2. In a process for concentrating calcite from an ore containing also mica and quartz, the step of agitating and aerating an aqueous pulp of the said ore with oleic acid and per ton of ore, from 0.05-2.0 1b. of isobutylglycolate.

3. In a process for concentrating calcite from an ore containing also mica and quartz, the step of agitating and aerating an aqueous pulp of the said ore with oleic acid and, per ton of ore, from 0.05 to 2 lb. of cyclohexyl glycolate.

4. In a process for concentrating calcite from an ore containing also mica and quartz, the step of agitating and aerating an aqueous pulp of the said ore with oleic acid and, per ton of ore, from 0.05-2.0 1b. of dodecyl glycolate.

5. In a process for concentrating hematite from an ore containing siliceous impurities, the step of agitating and aerating an aqueous pulp of the said ore with alkyl amine hydrochlorides derived from coconut oil fatty acids, and per ton of ore, from 0.05-2.0 lb, isobutyl glycolate.

6. In a process for concentrating copper sulfide ore, the step of agitating and aerating an aqueous pulp of the said ore with potassium ethyl xanthate and per ton of ore, from ODS-2.0 lb. of isobutyl glycolate.

'7. In a process for concentrating molybdenite me, the step of agitating and aerating an aqueous pulp of the said ore together with from 0.05-2.0 lb /ton of isobutyl glycolate.

form C. WOODHOUSE. 

